I was referring to his real number, which isn't in his FB account, but is likely stored in his friends' contact lists on their phones, which they in turn give o

I was referring to his real number, which isn't in his FB account, but is likely stored in his friends' contact lists on their phones, which they in turn give over to facebook. This lets FB create a shadow profile for him. Even if they don't associate that number and shadow profile directly with his fake profile, they will see that they have the same social circle, since the same group of friends will both have his real phone number in their contacts, and also be communicating with his fake profile through FB. At best, there's only two steps between his real phone number and his fake profile.